/*
 * Copyright (c) 2013, OpenCloudDB/MyCAT and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software;Designed and Developed mainly by many Chinese
 * opensource volunteers. you can redistribute it and/or modify it under the
 * terms of the GNU General Public License version 2 only, as published by the
 * Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Any questions about this component can be directed to it's project Web address
 * https://code.google.com/p/opencloudb/.
 *
 */
package io.mycat.util;

/**
 * (created at 2010-7-21)
 *
 * @author mycat
 */
public final class Pair<K, V> {

  private static final int HASH_CONST = 37;
  private final K key;
  private final V value;

  public Pair(K key, V value) {
    this.key = key;
    this.value = value;
  }

  public K getKey() {
    return key;
  }

  public V getValue() {
    return value;
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("(").append(key).append(", ").append(value).append(")");
    return sb.toString();
  }

  @Override
  public int hashCode() {
    int hash = 17;
    if (key == null) {
      hash += HASH_CONST;
    } else {
      hash = hash << 5 + hash << 1 + hash + key.hashCode();
    }
    if (value == null) {
      hash += HASH_CONST;
    } else {
      hash = hash << 5 + hash << 1 + hash + value.hashCode();
    }
    return hash;
  }

  @SuppressWarnings("rawtypes")
  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (!(obj instanceof Pair)) {
      return false;
    }
    Pair that = (Pair) obj;
    return isEquals(this.key, that.key) && isEquals(this.value, that.value);
  }

  private boolean isEquals(Object o1, Object o2) {
    if (o1 == o2) {
      return true;
    }
    if (o1 == null) {
      return o2 == null;
    }
    return o1.equals(o2);
  }

}